Color photographic paper is used in a wide variety of photoprocessing machines, which include large-scale processors capable of providing large volumes of photographic prints under conditions of continuous operation, and small-scale processors that are used to produce smaller volumes of photographic prints under conditions of discontinuous operation. These machines are known to differ widely in mechanical design, and the operating conditions for these processors vary widely in ambient temperature and humidity due to the wide variety of environments for use.
To provide a color photographic paper that serves all the different machines and conditions and is tolerant of the wide fluctuations in environment, one must address the variation of color paper performance to changes in heat and humidity at the site of operation. One aspect of these variations relates to the sensitivity of the photographic paper to changes in heat. It is desirable to make photographic materials that are invariant to any changes in environmental temperature, such that the photographic response does not change when the ambient temperature fluctuates during the course of processor operations. Alternatively, satisfactory results can-be achieved when the photographic response is neutral with respect to changes in environmental temperature, that is, although the photographic material may have a different response as the temperature changes, the changes are not noticeable to the operator as the effects of temperature in each of the constituent layers are synchronized to annul the effect of the temperature changes.
In the manufacture of color photographic paper it is critical to maintain the activity of the photographic components such that the photographic response does not change during the course of manufacturing. To ensure a consistent outcome is obtained, it is necessary to monitor photographic activity in the process of manufacturing. During the course of manufacturing, many incidental changes can occur and impact photographic response characteristics such as photographic speed. These speed changes can be measured during the manufacturing process, and adjustments can be made to maintain a consistent response. It is of enormous benefit to the process of manufacturing photographic materials if adjustments to the levels of the components bear a linear response to the speed value. Additionally, it is obvious that if less material is utilized in obtaining the desired photographic effect, cost advantages can be accrued.
Advantages gained in the manufacture of color paper cannot be realized if photographic performance is jeopardized. Therefore, it is desired that manufacturing gains be made concomitantly with gains in photographic performance. It is known that visual sharpness of the photographic material is critical to its acceptability for use, and that changes in sharpness or detail can occur when changes are made in the process of manufacturing; thus, it is highly desirable that manufacturing changes do not degrade sharpness, and it is even more desirable that such changes lead to improved sharpness.
It is intended that color photographic paper satisfy the desires of photographers in the practice of their art. In the hands of the photographer it is common practice to regulate the exposure of photographic material under conditions where some areas of the print may receive greater light exposure than a normal exposure to "burn in" the desired image to a greater degree. Alternatively, it is also the practice to shield some areas of the print from normal exposure to light, and by "dodging" the light in this way create the desired image. In practicing the techniques of dodging and burning, the photographer or enlarger operator is hindered by the present color photographic material that has a dark color content prior to exposure. Color papers also vary in their undeveloped color from batch to batch, as different absorber dyes are added to adjust their properties. This makes the dodging and burning more difficult, as the paper looks different during exposure as the undeveloped paper color is different.